The modern mobile communication is increasingly tending to provide diversified services for users. Currently, the Department of Public Safety of America has taken an LTE network as the basic communication network of its public safety communication service. A proximity-based service among UEs is an important part of public safety communication demand, including proximity discovery among UEs and proximity communication among UEs. As the basis of direct communication among UEs, the proximity discovery among UEs can judge whether another friend user exists around a user and prompt the user to conduct a next operation. In the field of public safety, the proximity discovery among UEs facilitates members of the execution sector of public safety to command a task and cooperate with each other in a specific field environment, and also provide safety by confidential means. Moreover, in a commercial field, the proximity discovery among UEs can be flexibly applied. It can support rapid formation of a regional social network, such as mutual discovery among proximate users with the same interests, or proximate promotion of commercial advertisements, etc.
FIG. 1 is a schematic view of the structure of an existing method for proximity discovery among UEs.
A user equipment (UE) 101 is a terminal equipment for supporting a proximity-based service with abilities of proximity discovery and being discovered.
The Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 102 is a wireless access network, including a macro base station (eNodeB) providing the UE with the access to an interface of the wireless network, which can provide resource allocation control while a proximity discovery service is being performed on the user equipment (UE) 101.
The Mobile Management Entity (MME) 103 is responsible for managing the mobile context, session context and security information of the UE, which can support service request validation while the proximity-based service is being performed on the User Equipment (UE) 101, provide an identifier list permitted to be found, allocate a to-be-discovered identifier, and direct the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 102 to conduct the resource allocation control on the user equipment (UE) 101.
The Home Subscriber Server (HSS) 104 is a subsystem of the UE, which is responsible for storing user information, such as the present location of the UE, the address of a service node, the user security information and the packet data context of the UE, as well as the subscription information of the service that the user may access.
The Proximity-based Service Subscriber Server (PSS) 105 is responsible for storing user information, such as the UE and the to-be-discovered identifier used presently by a proximity-based service user as well as the security information and the context of the proximity-based service for the user. The PSS can be an independent node, or co-located with the HSS or the MME.
The method for proximity discovery among UEs can be recognized as part of the proximity-based service, which may be provided for the UE or the user. In the proximity-based service, a readable proximity-based service identifier can be configured as the only identifier for the UE or the user. Specifically, when the proximity-based service is provided for the UE, a proximity-based service identifier can be configured for the UE as the only identifier of the UE in the network. When the proximity-based service is provided for the user, a proximity-based service identifier can be configured for the user as the only identifier of the user.
In the method for proximity discovery among UEs involved in the present invention, configuration of the to-be-discovered identifier for the UE aims at identifying the UE in the process of the proximity discovery among UEs. For the to-be-discovered identifier of the UE, it is acceptable to directly adopt the proximity-based service identifier or take a user application identifier of an application used for calling the proximity-based service. Certainly, in terms of security, it is also acceptable to configure for the UE the to-be-discovered identifier different from the proximity-based service identifier or the user application identifier.
FIG. 2 is a flow chart of the existing method for proximity discovery among UEs based on the structure shown in FIG. 1, including the following steps.
Step 201: A first UE activates a to-be-discovered function, initiates a registration process to a device to device (DTD) server, and obtains a DTD identifier and an expression code of the first UE. In addition, the first UE can further obtain DTD identifiers and group identifiers of other UEs.
A DTD identifier of a UE is configured by the DTD server, which can have various forms. For example, the DTD identifier may be a globally unique identifier, or an identifier having a corresponding relationship with a user identifier of 3GPP, or an identifier being the same as the user identifier of 3GPP.
The expression code of the UE is the identifier of the UE to be discovered for identifying itself in a broadcast signal, which can be the same as or different from the DTD identifier of the UE.
The identifiers of other UEs, in the example, may be an identifier of a second UE.
The group identifier is used to identify a group to which the first UE and the second UE belong.
The first UE activates a to-be-discovered broadcast mode, and a user may have two modes: a discovery mode and a to-be-discovered mode. The to-be-discovered mode refers to that the user broadcasts discovery signals. The discovery mode indicates that the user receives the discovery signals broadcast by other users and when required, sends a message of “proximity indication” to a user to be discovered.
In FIG. 2, the present invention is detailed with an example that the first UE activates the to-be-discovered mode and the second UE activates the discovery mode.
The DTD server sets the to-be-discovered identifier of the first UE. The to-be-discovered identifier is used to identify the first UE in the process of the proximity discovery among UEs. The to-be-discovered identifier can be a fixed identifier or a temporary identifier. The discovery signal broadcast by the user to be discovered can include the to-be-discovered identifier.
Step 202: The first UE broadcasts a to-be-discovered message within a scope to be discovered according to the resources used for DTD discovery configured by the network.
The resources configured by the network may include, but are not limited to, a frequency point, a time slot, a frame, a reuse mode, and power.
The UE can change the scope to be discovered by adjusting the transmission power and other radio parameters.
The broadcast contents may include one or more of the following messages: a DTD identifier of the UE to be discovered, namely the DTD identifier of the first UE; an expression code of the UE to be discovered, namely the expression code of the first UE; a DTD identifier of the discovering UE, in the example, the DTD identifier of the second UE; and a group identifier.
Step 203: The second UE activates a discovering function, initiates a registration process to the DTD server, and obtains the to-be-discovered identifier, the group identifier and other information of the first UE to be discovered. After the registration, the second UE obtains resources used for DTD discovery configured by the network from a serving base station.
Step 204: The second UE activates a discovery monitoring mode, monitors the broadcast in the proximity of the second UE, and obtains a to-be-discovered identifier of the broadcast.
According to the to-be-discovered identifier of the first UE in the monitored broadcast of the first UE, the second UE can identify that the first UE is a UE the second UE wants to discover. Alternatively, if the broadcast contents of the first UE include the identifier of the second UE, it denotes that the first UE wants to search whether the second UE is nearby. The second UE sends a response message to the first UE, indicating that the second UE is in the proximity of the first UE and can receive a signal broadcast by the first UE.